AI Reveals Thymus Gland’s Unexpected Role in Adult Health and Cancer Treatment

For decades, the thymus gland—crucial for immune system development in childhood—was believed to become largely inactive in adulthood. Though, groundbreaking research from Mass General Brigham investigators challenges this long-held assumption. Utilizing artificial intelligence (AI) to analyze routine CT scans, researchers have discovered that a healthy thymus in adults is linked to increased longevity, a reduced risk of cardiovascular disease and cancer, and improved response to immunotherapy.

The Rediscovery of the Thymus

The findings, published in two papers in the March 18, 2026 issue of Nature, suggest the thymus plays a more significant role in adult health than previously understood and could become a new target for disease prevention and personalized cancer treatments. “The thymus has been overlooked for decades and may be a missing piece in explaining why people age differently, and why cancer treatments fail in some patients,” said Hugo Aerts, PhD, corresponding author on the papers and director of the Artificial Intelligence in Medicine (AIM) Program at Mass General Brigham.

How the Research Was Conducted

The thymus, located in the chest, is responsible for training T cells, which are vital for immune function. Previous research focused on T cell diversity through blood-based analyses, but the new studies took a broader approach. The team analyzed data from over 25,000 adults participating in a national lung cancer screening trial and more than 2,500 participants in the Framingham Heart Study—a long-term study of cardiovascular health.

Researchers developed a “thymic health” score based on the size, shape, and composition of the thymus as seen on CT scans. Individuals with higher scores demonstrated a significantly lower risk of mortality and disease.

Key Findings: Thymic Health and its Impact

• Longevity: People with high thymic health scores had approximately a 50% lower risk of death.
• Cardiovascular Health: A 63% lower risk of cardiovascular death was observed in those with high thymic health.
• Lung Cancer Risk: Individuals with high thymic health had a 36% lower risk of developing lung cancer.
• Immunotherapy Response: Patients with stronger thymic health had a 37% lower risk of cancer progression and a 44% lower risk of death during immunotherapy treatment.

Lifestyle Factors and Thymic Health

The analysis revealed associations between lifestyle factors and thymic health. Chronic inflammation, smoking, and higher body weight were linked to poorer thymic health, suggesting that these factors may impact immune resilience throughout life.

Future Research and Clinical Applications

While these findings are promising, researchers caution that further studies are needed to confirm the results and develop the imaging method for routine clinical use. Current research is investigating whether radiation exposure during lung cancer treatment may affect thymic health. “Improving our understanding and monitoring of thymic health could eventually help physicians better assess disease risk and guide treatment decisions,” said Aerts.

About Mass General Brigham

Mass General Brigham is an integrated academic health care system dedicated to solving complex medical problems. It encompasses academic medical centers, community and specialty hospitals, a health insurance plan, and research initiatives, including a strong focus on artificial intelligence. Mass General Brigham is committed to patient care, research, teaching, and community service.